Project Summary/Abstract Over 400,000 patients are treated for sudden cardiac arrest each year in the U.S., but fewer than 1 in 5 survive after in-hospital cardiac arrest (IHCA), and fewer than 1 in 10 survive after out-of-hospital cardiac arrest (OHCA). The overwhelming majority of deaths are caused by failure to achieve return of spontaneous circulation (ROSC) using standard cardiopulmonary resuscitation (CPR) and advanced cardiovascular life support (ACLS). Extracorporeal cardiopulmonary resuscitation (ECPR) using percutaneous veno-arterial extracorporeal membrane oxygenation (ECMO) is rapidly emerging as a feasible and effective resuscitation strategy for patients that fail standard resuscitation efforts. It is estimated that up to 10% of treated OHCA and IHCA patients are potential candidates for ECPR, and widespread implementation could save up to 10,000 lives each year in the U.S. Although return of a spontaneous heartbeat can be initially achieved in most patients with ECPR, less than one third survive with good neurologic outcomes. Therefore, more research is needed to maximize the potential of this life saving therapy. A fundamental barrier to the success of ECPR after prolonged cardiac arrest is the ?no- reflow phenomenon,? defined as inadequate vital organ reperfusion despite restoring normal cardiac output. This project's central hypothesis is that intravascular complications of total-body ischemia and reperfusion, including microvascular coagulation, leukocyte-adhesion, and neutrophil extracellular trap (NET) formation cause no- reflow and prevent recovery of heart and brain function when ECPR is used to treat prolonged cardiac arrest. Our proposed Specific Aims will test this hypothesis in a clinically relevant swine model of ECPR after prolonged cardiac arrest that is established in the UM investigator laboratories. Aim 1 will elucidate the impact of intravascular coagulation on recovery of heart and brain function after prolonged cardiac arrest treated with ECPR. Experiments will: 1) compare the effectiveness of indirect (heparin) and direct (argatroban) thrombin inhibition early during CPR and 2) evaluate the effectiveness of thrombolytic therapy (streptokinase) at initiation of ECPR. Aim 2 will examine the impact of leukocyte-mediated inflammation on recovery of heart and brain function after prolonged cardiac arrest treated with ECPR. Proposed experiments will compare the effectiveness of standard leukocyte filtration to our novel leukocyte modulation (L-MOD) device during ECPR. Aim 3 will determine the impact of therapies identified in Aim 1 and Aim 2 on 7-day survival, cardiovascular function, and neurologic function after prolonged cardiac arrest treated with ECPR. Overall, the results of these aims will advance the field by providing new fundamental knowledge about the mechanisms of no-reflow and proof-of- concept evidence that therapeutic strategies effectively targeting ?no-reflow? improve outcomes with ECPR after prolonged cardiac arrest. This study results will serve as the foundation for pre-clinical optimization studies and, ultimately, clinical trials that will bring new therapies to the field with the goal optimizing outcomes after prolonged cardiac arrest.